Stencil for use in sandblasting



Feb. 1, 1938. R. H. KAVANAUGH 2,105,931

STENCIL FOR USE IN SANDBLASTING Filed March 20, 1956 Wm W 6 Patented Feb. 1, 1938 UNlTEl) STATES Parser oFr cEE dresser STENCIL FOR use in ssnnnms'mzo Robert H. Kavanaugh, Brewer, Maine Application March 20, was. Serial No. seen 3 Claims. ((31. EL-39) The object of this invention is to improve the production of designs on the surfaces of bodies of stone, wood, metal, encaustic tiling, leather, or of any other material the nature of which is 5 such that its surface may be abraded by the well known action of a sand blast. The invention comprises a stencil made of strands covered with sand blast resistant material and carrying a mask or masks of sand blast resistant material.

10 The stencil may be provided with a single aperture constituting the design, and receiving only one mask, or with a. plurality of apertures collectively constituting the design and receiving a corresponding number of masks.

Of the accompanying drawing forming a part or this specification;-

Figure l is a perspective view of a stencil formed to be applied to a body surface and having a single aperture shaped to characterize a design; 20 Figure 2 is a section on line 2-2 oi Figure 1;

Figure 3 is a perspective view showing the stencil of Figure l secured to the surface of a body to be ornamented, and a sand blast resistaim.v mask inserted in the stencil aperture;

Figure 4 is a section on line Q-d of Figure 3; Figure 5 shows the body in perspective and a relief ornament thereon formed by a sand blast, the stencil and the mask shown by Figures 3 and 4 being removed; 3O Figure 6 is a section on line 8-8 of Figure 5;

Figure 7 is a. perspective view of a portion of a body prepared for ornamentation in accordance with one embodiment of the invention;

Figure 8 shows a part of the body portion shown by Figure 7 after the application of the sand blast and after the removal of the protecting masks:

Figure 9 is a. section on line 5-9, Figure 7,-

showing the stencil used in the embodiment of the invention shown by Figure 7 40 Figure 10 shows the stencil in perspective;

Figure 11 shows a portion of a lace-like stencil and design-modifying masks applied thereto by the stencil, shown by Figure 10, the latter being omitted from this figure.

' 45 The same reference characters indicate the provided collectively characterizing the design as hereinafter described.

The stencil t is used by charging it with a piss tic mixture constituting a mask 8 which is resistant to a sand blast, the preferred nature of 5 the mixture being hereinafter described. The mask, filling the aperture 1, is shaped by the outlines of the aperture. It has cohesive and adhesive properties enabling it to adhere to the surface of the body t sufilciently to permit the sten- 10 oil to be removed from the body and. leave the mask in a predetermined position thereon. The mask material should be applied in the stencil 5 after the stencil is applied to the body.

A sand blast is directed against the body and 15V mask after the plastic resistant is dry, and after the removal of the stencil 5 and is caused to cut away portions of the body not protected by the mask, and thus form a depressed surface 9 (Fig. 6) outside the mask, a design iii in relief being left on the body portion protected by the mask.

Figure 10 shows a stencil is having a plurality cl apertures it collectively characterizing a denamented in the predetermined positions thereon modifiers to give them suilicient body and desirable qualities of consistency, plasticity, adhesiveness, etc. One-exampleof such composition consists of approximately sixty per cent. of latex,

preferably that known to the trade as "seventy per cent. latex compound" and forty per cent. powdered material suchat whiting or starch, (by measure). A small quantity of liquid glue is sometimes desirable to increase adhesion when applied to very smooth and non-porous surfaces,

such as glass for instance. When glue is em-. ployed, the proportions by measure may be. latex I fifty-five per cent, powdered material thirty-five per cent. and liquid glue ten per cent. While the glue somewhat hardens the mixture afterdry-- 7 ing, the hardening is not objectionable. Another suitable modifier is mucilage, or: its equivalent, such as gum arable, which may be used instead or glue and with or without a-content of powdered material ln'the'lateir'ihave found, that when a small quantity of gum arabic is added to seventy per cent. latex compound it cooperates with the latex in forming a heavy plastic mixture without the addition of whiting or other powdered material. The gum arablc gives body to the latex and increased adhesion, and enables the mixture to be readily washed from the stencil. Alternatively powdered casein may be used in the proportions of one part to each ten parts of the latex content, or thereabout. I have also found that formaldehyde mixed with latex, either the seventy per cent. compound referred to or preparations containing a smaller proportion of solids, modities the latex by giving it body enough to be used through a stencil as described A very small content of formaldehyde, in the order of one half teaspoonful to four fluid ounces of latex, (i. e., one 'per cent., more or less) is sufficient. If desired, a minor quantity of whiting or other suitable soft powdered material may be used with any of the above named latex preparations, or equivalent preparations.

I do not limit myself-to the described mask compositions, and may vary the same in any way suitable to produce a composition which has the qualities and capabilities hereinbefore mentioned; or use any other plastic substances than latex or a latex composition, provided the substance has like or equivalent properties; but I claim originality of invention in them and their substantial equivalents. I

Referring to Figures 7 to 11 inclusive. it will be seen that I apply to the surface to be ornamented protecting masks or patches l4, preferably composed, of a composition such as those previously described, or a substance having properties like those described, and formed to collectively characterize a design to be imparted to said surface by a sand blast. Other portions of the body are left bare and unprotected. when the body is of wood and a sand blast is applied, the unprotected portions of the body are worn away in such manner as to form grooves ll parallel with the grain of the wood as shown by Figure 8. The portions protected by the masks ll form smooth surface areas It which may be substantially flush with the ridges between the grooves l5, and retain the color and finish of the material of the body.

The stencil by which such masks are applied to the body may be of any suitable sheet material, as rubber or other soft pliable material, and is provided with openings it formed and arranged to.impart the desired design-producing form to the masks H, as may be seen by comparing Figure 10 with Figure 7. The plastic composition is sufficiently adhesive to cause the masks to adhere to the surface of the body with sumcient tenacity to permit the lifting of the stencil if from the body and the masks, the latter remaining on the body as shown by Figure 7. The sand blast is applied to produce the design, and finally the masks are removed from the now ornamented surface.

If desired, the molding stencil may be of the type described by my Patent No. 1,954,672, dated April 10, 1934; i. e., a reticulated lace-like structure; which, however,- need not be resistant to .sand blast, although it may be. The lace-like stencil It may be stiffened, as by impregnation with varnish, shellac, glue or other suitable impregnant, to maintain its shape so that it may serve as a matrix or mold, and it may be adhered by'a non-drying cementto the surface to be ornamented while the mask-forming plastic is pressed through its meshes When such a stencil has been removed, the plastic masks dried, and a sand blast driven against the surface worked upon, the lace design-is cut and sunk into the surface.

The design of the lace stencil may be modified by the addition to it of continuous areas or masks it, as shown in Figure 11, made of originally plasticmaterial in which strands of the stencil are embedded. The mask material here used may be any of the compositions or substances previously described, and when dry is permanently united to the strands and substantially flush on.

I, II and I2 may be coated with a suitable adhesive, preferably non-drying, to assist in holding it when the mask mixture is being applied to the stencil.

Each of the stencils, 5 and I2, may be made of material such as paper, rubber, metal or a suitable composition. The stencil may be rigid as when made of metal, or flexible as when made of paper.

The stencil whether flexible or rigid may be provided with a backing layer of soft flexible rubber or other soft'flexible material which when placed on a somewhat rough surfaced body 8 will conform to irregularities of the .body surface without leaving crevices into which the plastic mask material would be liable to work under the stencil.

Since stencils and masks or cover pads conforming with this invention may be applied tofsurfaces which have previously been coated with a thin film for protection of the mask covered surface and to facilitate removal of the mask, I wish to make it understood that statements in this specification and in the following claims, to the effect that masks are applied to the surface to be ornamented, are not intended to exclude the use of an undercoat or film with such masks and the like. Hence the term "surface and similar words or expressions used herein are to be con- I 2. A stencil for use in surface ornamentation by sand blasting comprising a reticulated core of threads or filaments covered by a casing of sand 3. A stencil for use in sand blasting comprising a reticulated fabric made of strands covered with sand blast resistant substance, and having a patch of sand blast resistant material in which certain of said strands are embedded.

ROBERT HZ KAVANAUGH. 

